Step 1) Getting the Page Count Right
In a PDF any given page is an isolated entity, you can copy out page 7 and it’ll free stand just fine. If you tear page 7 out of your favourite RPG* you’ll find page 8 comes with it, being printed directly on the back. Nothing you can do will separate those pages.
* Don’t do this.
If you were to carefully dissolve the binding glue and/or unstitch your favourite RPG** you’d find that what appeared to be letter sized sheets of paper are actually twice that large, and folded in half. There are, in fact, four pages printed on each sheet of paper.
** Don't do this either.
Your only options at this point are to have a bunch of blank sheets at the end, or to revisit your book design and find where you can organically add, or remove material to get the appropriate page length. The latter is a ton of work, the former is looked down on by both reader and publishers for whom it appears like a print error.
With Wireless Soul Transmission we made sure to end both our books on ‘printable’ materials like handouts and character sheets. Since we’re inclined to offer these as separate free downloads anyway (who photocopies out of a book in 2019?) we can either remove those pages from the print version, or include them, as necessary to make our page count.
Step 2) What Lies Beyond the Margin
So those ‘four pages to a sheet’ paper sheets the printer uses are actually even larger than I admitted. In a twist worthy of M Night Shyamalan, the paper goes at least an inch beyond the size of the paper you’ll ever see. A lot of this is called the ‘slug’ which both gives the printer (the machine, not the person) something to grip without damaging wet ink and gives the printer (the person, not the machine) somewhere to receive cutting/binding instructions and secret love letters that won’t end up in the end customer’s book.
Besides the slug, there is also the bleed (it’s like these things were named by a swamp witch). The super printers used by POD, much like yours at home, don’t want to print right to the edge because any slight variances in paper or print head alignment will lead to ink being sprayed off the side of the paper into the machinery. Machinery does not like this.
Fortunately, since the paper is already oversized, that won’t happen. In fact, the opposite will happen.
To get back to the paper size that the final book requires, the slug (and bleed) must be cut away. Here, again, small variations in paper alignment can cause the cut pages to not match perfectly with the page you see in your digital PDF. If you have an image that goes right to the edge it’ll be might be 1mm abbreviated on one side (no problem) and on the opposite side you’ll have a 1mm strip of super noticeable blank white paper (big problem).
And so finally we come back to the purpose of the bleed. To avoid this white strip, all images should actually go past the edge of your intended print area. This area of ‘extra image’ is called the bleed.
If you’ve prepared well, your art briefs will have requested images a little above the size you need. In practice you can still be caught out, sometimes there’ll be areas of an image around the border that you just aren’t prepared to part with. Readjusting these images to include sufficient bleed can be anywhere from a trivial matter to a total nightmare.
Step 3) Staying out of the Gutter
When your pages are printed they’re dipped in glue along the spine and set together. The area of the page that will be touched by the glue is the ‘gutter’. You need to make sure your print-ready PDF doesn’t try to print anything in the gutter, not only will it be invisible but ink in the gutter prevents glue from bonding properly. If you’ve ever had a hard cover book come apart at the slightest provocation, it may have been because of this.
Besides the gutter itself, you also need to consider any content immediately adjacent to it. If you have an image spread across two pages, whatever lands in the middle of that image will disappear into the spine. If you have pages you expect to be photocopied, they need to be far enough from the edge that the reader can do so without breaking the books spine.
Step 4) Ink Density and Colour Adjusting
I’ve left the big one till last. Modern screens have an amazing depth of colour; Adobe Photoshop has a 32bit per channel RGB setting which offers a truly terrifying scale of colour possibilities. Something in the order of 79,228,162,514,264,300,000,000,000,000 (79 octillion) by my math, which is just a silly number. Octillions would be your go-to if you wanted to measure the weight of the Earth in grams.
Obviously, some amount of conversion is going to happen here. There’s a lot of complexities to this. For one thing you’re talking additive vs subtractive colour mixing. If you don’t remember grade 8 art, think of it this way: when your monitor wants bright white, it shines the brightest LED it can right into your retina and for hard black it turns off the light completely***, this is additive. By contrast if your printer wants white, it prints nothing – it cannot make the paper more white than it is – and if it wants black, it throws as much ink at that dot of paper as it can.
*** Not exactly, but let’s keep things simple for now.
Different printers, different inks and different papers will see these problems to varying degrees of severity. Offset printers typically provide a ‘colour profile’ to aid in the conversions, but POD print companies are somewhat notorious for not providing this information. Why? No one’s really sure and it seems everyone in the POD industry is sworn to secrecy.
Even if they did provide such a thing, there’s every chance that, on seeing the proof, some images would need adjustment. No colour profile is perfect for every image.
Adjusting image colour is both time consuming and challenging. Imagine you have two images in front of you, one is digital and looks great, the other is a print that is either too dark or washed out. You have to reduce the quality of the digital image in the correct direction based on the way the print looks. Your goal is to make the next print look better, by making the digital image look worse.
Again there are some tools you can use to make the process easier, but it will always have a fundamentally speculative component too it.
Step 5) The Waiting
When you produce your hypothetically print-ready PDF you send it off to your printer and they do some initial assessment and pre-production work before giving you a green light to order a ‘proof’. Proofs are basically just a ‘not for sale’ version of a book so you can see it before you make them available to the gaming world.
Unless you live downstairs at the print house, a proof can take anywhere between ten and thirty days to reach you. Once you receive that proof, you’ll want to make changes (colour adjustments for instance) and then order another proof.
Whether that second proof has fixed all the issues or not will have a huge impact on your ability to meet a release date (and this is why we haven’t given one yet for the print version of WST). Every time you need another proof, you’re at least three weeks to your production time.
Across the course of this article it should be apparent that print-on-demand is a huge investment of time and effort for what might be very limited rewards. Print on demand is not for everyone, but for the gamer it means a large number of RPGs that would never make the cut for offset printing are available in beautiful hardcopy. Better still, this is a technology that will only keep improving with time, becoming more viable and more accessible for a greater range of games.